The issue is reproducible with any TM (and language pair) as long as there is a fuzzy match coming from the TM, but it seems to be a UI issue (display in Lookup) rather than the actual result from DeepL because if we clear the target segment, click outside and click back into that segment, the result from MT in the Lookups will be correct.
The issue is not reproducible in Trados Studio.
Also this issue does not occur if creating the project using only DeepL MT without TM.