Is generic subutex less strong than brand suboxone? Ever since I switch I've experienced what feels like slight withdrawal by the end of the day

Different compounds. Suboxone is a compound that contains both subutex and when you switch over to subutex without the Naltrexone protection, you are putting yourself at risk for developing tolerance to the subutex alone. This could explain why you are feeling the effect wear off at the end of the day. You may also wish to take a look at some of your herbal supplements to see if they affect the blood levels of suboxone or subutex. There is always the chance that by being compounded differently, although the original doses of medications are the same, they may be absorbed somewhat differently in different formulations. Best wishes.
Subutex . The active ingredient is bupernorphine =subutex , suboxone has Naloxone in it. So that is one thing; if you're talking about generic suboxone or generic subutex, they are made by different generic companies. I have had patients sware that there is a major difference between the drugs. In some official sense the generic may be only 80% as effective as the brand name.