Well, it hasn't been officially canceled, officially they are calling it on hiatus:
However, reading between the lines it seems to be done. The woman who was writing the series seems to have stalled out on writing series 4 and I am sure Covid hasn't helped things.
But after Sanditon was totally unexpectedly un-canceled and revived I guess it's theoretically possible they might surprise us with continuing Victoria eventually. Though I am not getting my hopes up.