Phone overheating after an hour of gameplay

For last one week or so, I have been noticing my phone getting extremely overheated after around 60mins of gameplay. This heating is more evident while playing arenas. To be honest I haven't noticed heating while playing regular eq or aq. Even when i completed grandmaster's gauntlet, which took roughly 2 hours, i didn't see the overheating (Or i was way too excited about the rewards to notice anything else). Anyway, its really a problem during arena grinding which generally requires more than an hour. When the device gets extremely heated, the game starts lagging like crazy. Often the screen completely freezes for 3-4 seconds. When it happens, i have to put my phone down for it to cool down before continuing the grind which is very disruptive.

I did a test this morning to find out whether its an issue with my phone or this game.

Device - iPhone XS MAX (Updated to latest OS version)

Test 1 -
- Charged my phone to 100%.
- Closed all background apps.
- Played arena for an hour.

Result - As expected, phone got extremely overheated to a point i was feeling the heat on my fingers through the case.

Test 2 -
- Left my phone for an hour to fully cool down.
- Charged it back to 100%.
- Closed all background apps.
- Played pubg for ~40mins.
- Played marvel future fight for ~30mins.

Result - Phone was slightly warm which is normal after an hour of screen on time. But nowhere near as hot as it was in the previous test.

I am not gonna jump to conclusion and say that the game is causing the overheating issue. However, all evidence points to the game at this time. We did have an issue a couple of years back where iphones were getting overheated. I guess its worth looking into.

Anyone else facing similar issues? Please share here. If a lot of people are facing similar issues then I am going to open a support ticket.