Instant pot duo crisp multi cooker Duo Crisp with Ultimate Lid 13-in-1 Multi-Cooker & Air Fryer, 6.2L, Black

There seem to be two problems, and both appear to come from user error.
To convert between airfryer and multicooker, an inner pressure sealing cap needs to be removed/inserted. It has a significant plastic lug that some people manage to break off. It may be that new production has a metal rather than plastic tab, but the workaround is kinda obvious - just be careful with it!
There are also problems encountered with the lid safety interlock mechanisms sticking, preventing the lid from being opened. This seems to be due to sticky food residues getting where they shouldn’t - likely associated with starchy froth and inappropriate fast pressure release. With the inner pot being shallower than traditional Instant Pots, there is less headroom to give a margin for error. Just avoid the temptation to fast release when you shouldn’t (rice,beans,etc), don’t push to the capacity limit when pressure cooking and you should be fine. Yes the mechanism shouldn’t be designed such that it is susceptible to this, but again it does seem to be that the product doesn’t handle abuse gracefully.
At £87 it is a bit of a bargain, stainless steel pot included - especially when compared to the Ninja SmartLid models and their non-stick pots (and their questionable durability). (edited)