Most people seem to have problems with the fob getting stuck in. Typically, I have the reverse issue.

It's a regular but random occurrence regardless of which fob is in play. You’ve unlocked the car and sat down. Press the fob in… it gets ejected. Push it back in… it gets ejected. Turn it over, push it in… it gets ejected. Push it back in… it stays in and you can press Start. There is no rhyme nor reason as to whether you’ve tried once, five times, not turned it over, turned it over twice – there are occasions when its default response is just to Reject and Eject.

Other times, same situation but straight in and Start, no problem.

Is this the fob slot playing up, if so how much of the dashboard needs to come out to change it?

I would be tempted to give it a squirt with some silicone spray or something

Just for reference, the fob only charges when it's inserted buttons up.
A quick squirt silicone spray is what I'd try too, assuming the locking tabs on the fobs aren't damaged. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, the daily driver.
1972 Hillman Avenger GT, the project.