hi, dont know the material but its soft enough to push a fingernail into & leave a dent in the cuff area & tackiness is worse on the blue areas than the orange.
I'm guessing you may be seeing the dreaded rubber or plastic deterioration or oiling e.g. the paint gets affected because as the rubber/plastic itself gets greasy it would affect the paint. Especially since you say the material is soft enough to leave a dent.
If you look around the 'net and YT u can find different ways people have tackled the problem. Don't wanna bum you out but far as I can tell it's a chemical thing - you can slow it, maybe, not stop it really. In general seems like people (esp. w. Batman DX oiling) wipe and seal, same as you did.
Here's some older posts about that kind of thing:
https://www.sideshowcollectors.com/forums/general-collectibles-action-figures/82683-hot-toys-rubber-deterioration.html
https://www.sideshowcollectors.com/forums/archive/index.php/t-71433-p-2.html
Always the question why rubber toys from the '60s that were thrown into toy boxes and abused are still in good condition but at least some HTs have peeling pleather, cracking, oiling rubber, paint changes.
Far as I can tell as a side effect of collecting, collectors need to gather a repair kit together and have a list of favorite part sellers on the 'bay.
And favorite YT links of how-tos.
Edit - OK - looking at pics of the Disco - I'd still guess what you are seeing is plastic degrading. Either that or the paint itself is just *&^ like some bad paint that never fully cures.
Hope some others weigh in as just don't know enough - for me I guess I'd try just what you did. Or do a lot of research and see if there is a "drier" - a chemical that I know oil painters use - that maybe could "stiffen" the paint.
Sorry it happened, probably lots more info online if u look around.