Trouble with "weird taste" is that no one can work out what it tastes like from your description. Time to be a bit more specific. Ignore the word "weird" what does the taste remind you of ?
The BJCP material has enough descriptions of "off" flavours for you to think of some possible problems. Use them.
For the record, W-34/70 has been used millions of times and if it was really causing "weird tastes" this problem would have been picked up before. So, firstly, don't blame the yeast. Tell us what you did and how you did it, tell us what it tastes like and then someone may be able to address the problem.
Beer, it isn't everything, but it'll do till I get everything.
Never argue with a fool, onlookers may not be able to tell the difference.Mark Twain