Perhaps a moderator will move this out of "Engines" and into "Axles + Brakes".
Another possibility is mis-matched SAE and Metric threads.
Less-likely is a too-short or mis-routed/twisted brake hose that goes tight on turns, puts rotational stress on the hose-end.
TWO washers on each hose. One between banjo bolt head and hose end, one between hose end and caliper.Did anybody mention the washer?
Thank you. Saved me a bunch of typing.Thread the banjo bolt into the caliper without the hose or washers. Do not tighten. See how much it can wiggle from side to side. Should not be much. The threads in the caliper may be damaged from overtightening and this is a quick and dirty way to check.
Another possibility is mis-matched SAE and Metric threads.
Less-likely is a too-short or mis-routed/twisted brake hose that goes tight on turns, puts rotational stress on the hose-end.