Welcome to Android Central forums. Just a few questions to begin with.
What brand, make and model are the hearing aids?
The system update was for the tablet, correct? Was this an OS update, security patch, or what type of update was it?
How did you perform this update? Was it an OTA, manually, how?
While the device you're working with is an Android your question may be a little too specific to find anyone with actual experience with that device, who also is using hearing aids, and may have recently updated. My advice would be to get as close to one of the devices as you can vs. an open forum that discusses Android in general.
Doogee has a support page,
here, that might be a good place to ask a question, either directly about the recent update or in general about connecting to hearing aids. I would imagine that they have trusted moderators or community members that would know the device and it's updates better than we would.
I would also recommend seeing if your hearing aid brand has a forum or support page. I would look that up for you but we don't have the information needed to do that.
XDA, another Android device site, has a Doogee forum,
here, that has some recent posts, ironically with the most recent being "Don't buy Doogee devices" but others that are more recent than threads here at AC.
Alternatively, casting a wider net can sometimes be the ticket. There are a few thousand members here, with a handful helping to search for answers to member questions, where someplace like Reddit has millions of readers with so many willing to chime in on topics you might just find that other person out there who both uses this device and connects to it with hearing aids, maybe even the same brand you use. You can find a search for U11 topics
here, with the most recent being 21 days old.
I hate that I couldn't help more. Best wishes and good luck. Let us know what you find and hopefully we'll see you around for other discussions.