Toilet waste small drip leak - plumbers mait not working

I think you have some kind of ribbed insert that isn't quite where it should be (or needs replacing) and I'm not quite sure what I'm looking at. The bit on the right is logically a painted pan connector, but almost looks like a bit of cast-iron in this photo. It seems to insert into a piece of uPVC soil pipe, but possibly someone has inserted the ribs into a socket which is slightly larger bore than the pipe itself and may not really work correctly.

I'm not a fan of Plumbers Mait being used for plumbing-related purposes, and used in conjunction with plastic pipe it isn't the right material anyway. I'd suggest taking it all apart, cleaning it up, reassembling with a bit of silicone grease (or water or soap, if you must) as lubricant, and possibly a new pan connector, but if that is your only toilet, do you really want to DIY it?

It's not that it's not possible to DIY such a thing, it's that once you have it apart, it may be a while while you work out what you need to get it back together again. And if there is anything upstream of that connection, make sure you have some way of stopping water coming out from other appliances. Something like this is handy:

To be honest I’m a DIYer & not a plumber, but I would definitely not be confident enough to take this apart, & was looking for some sort of solution which would fix the issue in situ.

Denso tape

You could try making a bandage with a strip of cloth smeared with silicone sealant to make a form of sticky tape. I suppose if you then smeared the cloth with silicone after it had set, you might even make it reasonably hygienic in that you would have a smooth, wipeable surface.

Another vote for Denso tape.
In my youth I used Denso tape for a very similar fix. It was still holding over 35 years later.
A bit messy applying it though!
And on the hygienic point mentioned above, you would probably need to wrap it with plastic or something!!

Amazon productView: https://www.amazon.co.uk/Denso-Tape-50mm-Rolls-DENTAPE50MM/dp/B001OXDD6K/ref=asc_df_B001OXDD6K/?

You could wrap it with insulation tape to make it wipeable (you might even be able to fix the leak with insulation tape if you are skilled and nothing is moving. Ditto for duct tape, but probably harder to use.

You can get self-amalgamating tape, but expensive in the quantities you'd need.

I've heard good things about Denso tape too.