I regret it's too hard to tell Lulu, at least without more details. Please don't ask the Community to guess. We are a precision oriented users forum.
I won't ask why you would select a potentially long and challenging recipe for your first cook from an unidentified source.
When swimming in new waters would you dive in head first?
A more trustworthy recipe source might have alerted you to the evaporation issue in long duration cooks. All you can do is address the food safety probabilities using the facts only you know. They would be facts such as the meat's thickness and starting temperature, and either frozen or refrigerated.
You should be aware of the start time of actual cooking. If you can, estimate how long it cooked once the water temperature reached your set point of 150ᴼF before low water level occurred. Knowing that you will know if Pasteurization had been achieved giving you some margin of safety.
It's a long way from 150ᴼF to 86ᴼF even in a small amount of water. You might have been cooking in too small an uncovered vessel.
If there is any chance unpasteurized meat's internal temperature was below 130ᴼF for more than 3 hours it could be hazardous to consume.
You clearly have some work to do gaining knowledge of the SV technique.