ipad 9 is too difficult for apple: they need to upgrade screen, they need to upgrade SoC, they need to upgrade RAM, and they need to keep the price.
that is just too much of an upgrade.
people who use ipad 6 and ipad 7 as a logic behind keeping the same SoC (A10) don't see that A10 for ipad 7 was a mistake. it should have been A11, but apple decided to use A10 for whatever reasons. that is why they "skipped" a generation for ipad 8. but if ipad 7 would have had A11, it made for a steady SoC upgrade: ipad 6 / A10, ipad 7 / A11, ipad 8 / A12, ipad 9 / A13. so most probably ipad 9 will have A13, but the thing is it also have to be upgraded with laminated screen, and apple didn't fix ipad pro 10.5/air 3 spot issue. so they know 10.5 air 3 body will have issues. they also need to upgrade RAM, because 3Gb is just not futureproof anymore as of 2021.
so, as there are still no rumours about ipad 9 it seems apple still don't quite understand what to do with ipad 9. they got Pro, Air and Mini.. should they just ditch ipad altogether?) in other words, ipad 9 may not come to light any time soon.