PC slows to a halt after I play more than 1 game of Rocket League

Question

Here are my system specs.

System:    Host: mohammed-pc Kernel: 5.2.1-1-MANJARO x86_64 bits: 64 compiler: gcc v: 9.1.0 Desktop: i3 4.16.1 info: i3bar 
           dm: LightDM 1.30.0 Distro: Manjaro Linux 
Machine:   Type: Desktop Mobo: ASRock model: Z390M-ITX/ac serial: <root required> UEFI: American Megatrends v: P1.10 
           date: 08/17/2018 
Battery:   Device-1: hidpp_battery_0 model: Logitech Wireless Mouse MX Master 2S serial: 4069-26-02-73-2b 
           charge: 10% (should be ignored) rechargeable: yes status: Discharging 
CPU:       Topology: 8-Core model: Intel Core i9-9900K bits: 64 type: MT MCP arch: Kaby Lake rev: C L2 cache: 16.0 MiB 
           flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 115232 
           Speed: 4700 MHz min/max: 800/5000 MHz Core speeds (MHz): 1: 4700 2: 4700 3: 4700 4: 4700 5: 4700 6: 4700 7: 4700 
           8: 4700 9: 4700 10: 4700 11: 4700 12: 4700 13: 4700 14: 4701 15: 4700 16: 4700 
Graphics:  Device-1: NVIDIA TU102 [GeForce RTX 2080 Ti Rev. A] vendor: eVga.com. driver: nvidia v: 430.26 bus ID: 01:00.0 
           chip ID: 10de:1e07 
           Display: tty server: X.Org 1.20.5 driver: nvidia compositor: xcompmgr tty: N/A 
           OpenGL: renderer: GeForce RTX 2080 Ti/PCIe/SSE2 v: 4.6.0 NVIDIA 430.26 direct render: Yes 
Audio:     Device-1: Intel Cannon Lake PCH cAVS vendor: ASRock driver: snd_hda_intel v: kernel bus ID: 00:1f.3 
           chip ID: 8086:a348 
           Device-2: NVIDIA TU102 High Definition Audio vendor: eVga.com. driver: snd_hda_intel v: kernel bus ID: 01:00.1 
           chip ID: 10de:10f7 
           Sound Server: ALSA v: k5.2.1-1-MANJARO 
Network:   Device-1: Intel Ethernet I219-V vendor: ASRock driver: e1000e v: 3.2.6-k port: efa0 bus ID: 00:1f.6 
           chip ID: 8086:15bc 
           IF: eno1 state: down mac: 70:85:c2:a4:f4:8c 
           Device-2: Intel I211 Gigabit Network vendor: ASRock driver: igb v: 5.6.0-k port: 3000 bus ID: 02:00.0 
           chip ID: 8086:1539 
           IF: enp2s0 state: down mac: 70:85:c2:a4:f4:8a 
           Device-3: Intel Dual Band Wireless-AC 3168NGW [Stone Peak] driver: iwlwifi v: kernel port: 3000 bus ID: 03:00.0 
           chip ID: 8086:24fb 
           IF: wlp3s0 state: up mac: 3c:6a:a7:36:92:87 
Drives:    Local Storage: total: 5.60 TiB used: 4.83 TiB (86.2%) 
           ID-1: /dev/nvme0n1 vendor: HP model: SSD EX950 2TB size: 1.82 TiB speed: 31.6 Gb/s lanes: 4 serial: HBSE59101400335 
           rev: SS0221B scheme: GPT 
           ID-2: /dev/sda vendor: Seagate model: ST4000DM004-2CV104 size: 3.64 TiB speed: 6.0 Gb/s rotation: 5425 rpm 
           serial: WFN0GQ13 rev: 0001 scheme: GPT 
           ID-3: /dev/sdb type: USB vendor: SanDisk model: Ultra USB 3.0 size: 28.64 GiB serial: 4C530000310407119011 
           rev: 1.00 scheme: MBR 
           ID-4: /dev/sdc type: USB vendor: SanDisk model: Ultra USB 3.0 size: 28.64 GiB serial: 4C530000190407118521 
           rev: 1.00 scheme: MBR 
           ID-5: /dev/sdd type: USB vendor: SanDisk model: Cruzer Glide size: 28.65 GiB serial: 4C530000080610116371 rev: 1.00 
           scheme: MBR 
           ID-6: /dev/sde type: USB model: Walgreen Infinitive size: 58.73 GiB serial: 4C530001070126113545 rev: 1.00 
           scheme: MBR 
Partition: ID-1: / size: 1.76 TiB used: 1.43 TiB (81.7%) fs: ext4 dev: /dev/nvme0n1p2 
           ID-2: swap-1 size: 34.47 GiB used: 14.5 MiB (0.0%) fs: swap dev: /dev/nvme0n1p3 
Sensors:   System Temperatures: cpu: 77.0 C mobo: N/A gpu: nvidia temp: 55 C 
           Fan Speeds (RPM): N/A gpu: nvidia fan: 0% 
Info:      Processes: 341 Uptime: 5h 24m Memory: 31.33 GiB used: 14.02 GiB (44.8%) Init: systemd v: 242 Compilers: gcc: 9.1.0 
           clang: 8.0.0 Shell: fish v: 3.0.2 running in: kitty inxi: 3.0.34 

I have had this issue on both Arch and Manjaro, but I am not sure what is causing this. I don't think this is a hardware issue as this used to never happen. I also don't think it is an issue with the game as it works just fine on my laptop running Manjaro.

If I play 1 game of Rocket League, my PC is fine. However if I play 2 or more in a row then my PC is very likely freezes for no apparent reason during the second game. It becomes extremely slow and unresponsive and it takes a few minutes to even quit the game.

If I am doing offline training then it is fine. I have not tested this yet on local/bot games so so far I have only noticed it in online games. I don't really play any other games, so I have only noticed this in Rocket League.

I initially thought this this could be a memory leak, so I kept checking RAM usage during the game (via htop) and it never went above 5GB.

I know I didn't provide much information, but I don't know what else to add to be honest. If I need to provide anything else specifically, please feel free to ask.