Sounds like good ol' tree pee. Some form of precip got in with the sap and it discolours, but so long as it is clear and has no off-flavour or smell to it, it's fine to add and boil. Others dump it on principle, but I've never had a batch made with tree pee ever taste weird or go funky.
ETA: You don't even need for rainwater or snow to get in. I've had tree pee turn up as a result of meltwater from the trunk managing to drip into the bucket, esp if it was blown askew by wind.
Been tapping since 2008.
2018 - 17 taps/7 trees...819l sap, approx 28l syrup
2019 - 18 taps/8 trees...585l sap, 28l syrup...21:1 ratio
2020 - 18 taps/8 trees...890.04l sap...gave away about 170l, 30l snafu'd....23l total for me from approx 690l
2021 - 18 taps/8 trees...395l sap, 12 l syrup
2022 - 18 taps/8 trees....7 sugars 1 red due to #2 having surgery so had the season off....582l sap, 18.5l syrup
2023 - 18 taps/8 trees...all sugars again. 807l sap, so far approx 14l syrup