Which external hard drive to choose?

Hi there, I am (trying) to edit a documentary (total duration approx. 1 hour) on my home set-up: a MacMini M1, 2020, 16GB internal memory, 1TB hard drive. Looking for an external hard drive that is suitable for the workflow: the fcp-library will be located there so that the internal hd is not burdened. But which one to choose? Source material is hd and pretty huge. I tried the SanDisk Etreme Pro Portable (4 tb) but appeared to have glitches. Imag in fcp-viewer started flickering. Appreciate your advice!

I'm using that same Mini with an OWC Thunderbay 8, loaded with 4TB 2.5" SSDs in RAID 4. Had a minor scare with SoftRAID last fall, but it's been sorted. I keep a spare SSD in case one fails, and the whole thing gets backed up to LTO every night (incrementally, of course).