Keep receiving the "PS5 is too hot" message when playing certain games, even after sending for a check-up

About a month ago, I started to get this message of "PS5 is too hot" and to turn off the console until the temp goes down. It usually lasts a second until I can go back to the game, as if nothing happened. I have the old model PS5 for reference.

After starting to receive this message more frequently (usually when some heavy scene requiring a lot of loading happened, where the fan starts to roar) I decided to send it to someone for a check up, and after 2 days, they gave it back telling me that "they tried to remove the dust and do what they could, but because of the liquid metal, not much could be done". I have my doubts about that, but for now it seems to be working okay. A day later, it sent the message again, despite playing a less powerful game than normal.

Right now, I'm not sure what to do: I'm currently playing with one side panel off so that more air can enter, while also having a fan sending air directly to the fan, which seems to help a bit (it made the message appear much less). However, I can't play certain heavy games (like FF16), which will trigger the message more often than normal.

My PS5 was NEVER close to a wall, and in fact, I bought a small table that could be moved freely, so that I could put it anywhere I wanted, and it was at least 50cm away from the nearest wall, with a lot of space surrounding it, so airflow was never an issue.

I also did several tests, including using a thermometer, and temps barely reach 60C (140F) when playing heavy games. The absolute max was 67C (152F), and even then, it was for a brief moment, where sometimes the message would appear. I would constantly use compressed air to free the fan from dust, and generally speaking, I tried to keep a check on the heat to make sure it was well kept all the time, so I'm wondering if it's a big problem that can be solved, or something else entirely.

At the moment, it never turns off itself, and as long as I play small games (or even ps4 games), it doesn't seem to have trouble with heat.

I'm not sure whether to send for ANOTHER check (to someone else, that is), or just give up and move on.