QTGMC outputs blurry mess?
 

Slowly and surely converting VHS tapes to digital. Using StaxRip, I use QTGMC on the "Slower" preset.

But... It results in this sloppy blurry mess and it p*sses me off.

De-interlacing was never a lossless process, Quality always takes a hit whenever used, Try faster setting and see if it makes any difference.

A lot probably depends on the source. If it's a EP tape recorded from television, I could see that being roughly what it could look like. What was your capture setup?

Yes it is a EP tape recorded off television. Source tape is kind of degraded.

Workflow:
JVC S-VHS VCR
Temporary DVD Recorder (acting like TBC)
ION VIDEO MKII
Recorded with Lagarith in AmaRecTV

In this clip, I threw some heavy hitters at it. BasicVSR++, Dot crawl filters, DeRainbow filters, MCTempDenoise

Also attached is the original .AVI

Stop using preset="slower", as it has aggressive NR.