I didn't find any task regarding saving exif metadata. There are multiple interwired issues.

Relevant bug reports and wishes:

413970 krita General krita-bugs-null@kde.org CONF --- No EXIF data for TIFF images 2019-11-09 0
410341 krita General krita-bugs-null@kde.org CONF --- Exif checkboxes ‘Fired’, ‘Function’ and ‘Red-eye remove’ all act as *one* checkbox 2019-09-26 0
396669 krita File for krita-bugs-null@kde.org CONF --- Problem with Metadata in JPEG Export 2019-09-23 0
396672 krita File for krita-bugs-null@kde.org CONF --- Krita does not save metadata of imported images 2018-09-15 0

The one about checkboxes is not only a view issue: it showcase that the dialog is wrongly written, the view is not separated from the model etc.

https://bugs.kde.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=CONFIRMED&bug_status=ASSIGNED&bug_status=REOPENED&bug_status=NEEDSINFO&f0=OP&f1=OP&f10=OP&f11=OP&f12=product&f13=component&f14=alias&f15=short_desc&f17=content&f18=CP&f19=CP&f2=product&f3=component&f4=alias&f5=short_desc&f7=content&f8=CP&f9=CP&j1=OR&j11=OR&list_id=1732779&o12=substring&o13=substring&o14=substring&o15=substring&o16=substring&o17=matches&o2=substring&o3=substring&o4=substring&o5=substring&o6=substring&o7=matches&product=krita&query_format=advanced&v12=exif&v13=exif&v14=exif&v15=exif&v16=exif&v17=%22exif%22&v2=krita&v3=krita&v4=krita&v5=krita&v6=krita&v7=%22krita%22