Same size as a normal ISA connector but "deeper" (2 rows of contact if you could inspect them)? EISA

Full ISA connector (potentially missing the bit in the middle) and then a further piece? VLB

Shorter than ISA but higher density? AGP (it's even a bit shorter than PCI)

Was it at least a Pentium? Can't be AGP otherwise.

Going to ignore PCI-X, PCIE and obscure AGP variants

I was talking about what was on the card itself rather than the interface, because the poster I was responding to mentioned the card, but your point about interfaces is well made.

Back in the day - late 80s, very early 90s - I’d see Amstrad (ugh!) 286-based desktop systems on sale in our local branch of Dixon that included graphics cards fitted with VGA chipsets, but cards compatible with the AGP interface on then newer motherboards didn’t cross my radar until the second half of the 90s.

ISA slot, likely.

Is it possible it could’ve been EISA and that’s why it seemed different?

I can’t remember if those were available on 386s or started in the 486 era.

A Local bus ? The VESA Local Bus (VLB) was a thing in 486 boards and, I think, early Pentium boards. but was predated by privative local buses. I don't know if there was one on 386 boards.

EISA was typically reserved for higher end server and workstation type motherboards. Consumer-grade PCs never really got to experience EISA.

AGP came too late for the 486. It may have been VLB, a short-lived step between ISA and PCI (and then AGP).

I just looked up a few old motherboards and I think you are correct! I remembered it was a brown PCI-looking bus and incorrectly assumed the only thing that matched was AGP - the VLB looks exactly like what I remember.