I suspect as a small company, JLR have been buttoppsed by the (ex) 2030 rules, and worked to that and never came up with new engine designs for the past decade. Those engines are probably all showing their age, especially some of the older petrols. I think in the RR, they went back to BMW V8's to save developing something themselves for the short term.
What has seemed to bugger them up is the new EV isn't ready yet. Dunno why - have they delayed because they know the market isn't ready yet, or is it design issues?
Not sure I understand their apparent strategy though, as they have given up on being mass market manufacturer, hence the demise of all their saloon models that sold well to fleets, and want to be an unaffordable premium brand. Trouble is, they can't do that with their current quality issues*, and the utter crapness of their dealer network. The cynic in me is this is a part ploy to get rid of most of the dealers, as they will have nothing to sell.
*Granted, it's their suppliers. But they chose their suppliers, and thus have a say on what the quality should be.