Standing toilet is leaking - seal between siphon and pipe is not tight

After about 25 years, the toilet started to drip. The picture shows the installation situation of the standing toilet. The seal between the siphon and the first pipe no longer sealed. After I pushed it in a bit further with my finger, everything was fine again. Is everything okay now, or should I do something else? Thank you

Contract a plumber to replace the gasket.

After 25 years, a rubber seal may become porous. I think the seal should be replaced here. If you think you can do it yourself, try it, but remove the water first. Otherwise, consult a trusted professional before you start fiddling.

Thank you for the tips!

Now the spot has been sealed for almost a month. Apparently, simply pressing the seal with a finger helped.

Since the spot is not under pressure, it is only the wastewater after the siphon, I am not changing anything at the moment.

To notice more quickly if it should start dripping again, I have placed kitchen paper underneath.