Othazite was simply benzotriazole. I use it in power form. A tiny bottle of powder lasts a long time. You need very little of it, only about 10% per gram weight as when formulas call for KBr. Formulary sells benzotriazole per se in its bulk chemical selection.
Regarding that TAF product, it's easy to find out. The legally required MSDS sheet on their own website shows benzotriazole as a prime ingredient. Usage-wise, there are associated technical sheets. I gotta disagree, however, about their assessment of the interaction between benz and amidol based on the old Brett Weston formula, which confused the issue with a lot of redundant sodium carbonate added as an alkaline accelerant. I know how the get around that.
For some people, having the convenience of pre-measured packets makes more sense than needing to carefully weigh tiny amounts of powder.