[V2.17] Text and Icon rendering corruption

Nobody has claimed this yet.

Some of our users are reporting an intermittent issue where all map text is corrupted or missing. This is affects both rendered labels and lines.

It looks like the Font->glyph map isn't aligning or has a DPI mismatch?
The font in the screenshot was "**DIN Pro Medium**". Restarting the app fixes the issue. We've observed the issue on both Android and iOS, (Screenshot is IOS):

Steps to reproduce the Rendering bug (happens 100% of the time):

1) Open a mapbox map (even the mapbox studio sample app has the bug)
2) Minimise the application, and launch another app (e.g photos)
3) Use the task switcher to go back to mapbox
4) Pan the camera, notice no new map data downloads, eventually you are left with a dead map

Unfortunately I don't have the steps to reproduce the Glyph corruption bug, it seems intermittent and seems to occur after switching back to the application.

IOS:

Mapbox Studio

Start by reproducing the documented app-backgrounding sequence in the Mapbox Studio sample and the Flutter app on iOS and Android. Investigate the map lifecycle after returning from the task switcher, then compare that behavior with the intermittent glyph corruption; done means map data resumes downloading and labels and lines render correctly without restarting the app.

Written by the indexing model from the issue text.