Unfortunately Fluorocarbon lines are more likely to break at the knot and that’s just how it is.
I line test the lines I used off my fish scale. So I get results that applies directly to how I tie my knots and on which line.
Gamma Touch .16 mm 4# line break 3# 10 oz. (palomar knot 3# 9 oz.)
Gamma Touch .19 mm 5# line break 4# 14 oz. (palomar knot 4# 5 oz.)
Pline Flouroice .15 mm 3# line break 3# 3 oz. (2011-2yr 3# 9 oz.) (2015 7 yrs 3# 7 oz.)
Pline Floroclear .16 mm 3# line break 4# 1 oz. (2012 palomar knot 4# 4)
Pline Floroclear .18 mm 4# line break 5# 14 oz. (2012 palomar knot 6#1)
Pline Floroclear .23 mm 6# line break 8# 11 oz. (2012 palomar knot 8#1)
Pline Floroclear .25 mm 8# line break 10# 9 oz. (2012 palomar knot 10#1)
ASSO Micron 3 .153 mm 4# knot break 4# 8 oz. Mfg claim break of 4.8# (2011-1 yr 4# 12 oz.)(2015-5yrs 4# 7 oz.)
ASSO Micron 3 .173 mm 5# line breaks 5# 2 oz. Mfg claimed break of 6.2#
How long the line lasts in years? Pretty amazing that fluorocarbon stuff, even just coated version. Off the same reel spool just pulled a few feet to get to somewhat more fresh line and it’s still pretty strong after 5 years. Of course everyone’s mileage may vary. That was back in 2015…and I still have some of those same lines on some reels. Just have to test them again before going fishing.