Question Files are copied slowly, while folders are copied at normal speed from external HDD ?

Sep 23, 2021
I've got a Western Digital 1.5 TB USB 3.0 External HDD (WDBU6Y0015BBK-WESN) and I'd no problems with performance whatsoever until last week, when read speeds started to slow down for files that were copied dropping to about 8-9 MB/s (~ USB 2.0 speed), but copying folders gives me ~ 100 MB/s (the usual speed). I tried running crystal disk mark benchmark and I got normal speeds I used to get earlier for both sequential and 4k random speed tests. I tried installing TeraCopy, to check the speeds where I get capped at ~ 30 MB/s no matter I transfer a file/folder to or from the eHDD. I tried all the trivial stuff i.e., defragmentation, error checking, it was actually listed as USB 3.0 in Windows (in multiple places).

Maybe a quick format MIGHT help me, but I've got no place to copy all my data from the ext HDD and don't want to loose it. If there is something that can be done, could you please help me with this issue? Thanks.
P.S. - I can upload any images in case you need...