cannot get my iPhone 11 to vibrate on incoming silent calls anymore

You suggest you've tried everything suggested, but without telling us what that includes, it's hard to advise you very well.

For example, in Settings > Sounds & Haptics > Haptics, is it checked next to Play in Silent Mode?

What do you have set for how to change volume? For example do you have Change with Buttons turned on and if you do, I'd recommend you turn that button off.

If both are as suggested, yes, you can speak with Apple. You can call them (this is in the US) at: 800-MY-APPLE or schedule an appointment at your Apple Store Genius Bar.

Ps: NO ONE has been argumentative with you. You haven't provided enough information for anyone to magically solve this for you, however.

MaryAnnUK wrote: "...I assume this is because of the latest update..."

MaryAnn ~ Before assuming that, consider that your iPhone 11 could be 5½ years old and the long process of applying an iOS update to an iPhone with a weak, aging battery can be the proverbial "straw that broke the camel's back." So...

Does your iPhone 11 still have its original battery?

And what's the Maximum Capacity % here?...

Settings > Battery > Battery Health & Charging

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MaryAnnUK wrote: "My iPhone is about 1 year old..."

MaryAnn ~ No, your iPhone 11 is not "about 1 year old." Presumably you mean that you acquired it about a year ago. And its 87% maximum capacity implies that the battery has been replaced. To see if that's the case, go to Settings > General > About

...Does it say anything about the battery?

iPhone parts and service history - Apple Support

...Found by searching Apple's Knowledge Base.

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MaryAnnUK wrote:

My iPhone is about 1 year old, with an original battery at 87%. Everything else on it works just fine. It’s a very fundamental and basic function of the phone and I have seen people refer to this is a problem since they did an iOS update. But What is a solution, because none of the haptics and accessibility suggestions work for me (and some others too)? Is there a way to contact Apple to clarify what the problem Is?

As Alancito correctly suggests, it would not be possible to have iPhone 11 which is about 1 year old. iPhone 11 was released in 2019 and fully discontinued by Apple in 2022.