I don’t deny that many, maybe the majority, view UBI as unconditional. But to say ALL define UBI this way is a really strong statement, do you have any proof?
Here an example I found on Britannica:
Uganda’s UBI trial, the Youth Opportunities Program, enabled participants to invest in skills training as well as tools and materials, resulting in an increase of business assets by 57%, work hours by 17%, and earnings by 38%.
Christopher Blattman et al., “Generating Skilled Self-Employment in Developing Countries: Experimental Evidence from Uganda,” ssrn.com, Nov. 14, 2013
Link: https://www.britannica.com/procon/universal-basic-income-UBI-debate
If definition was so important to me, I could argue with you what unconditional really means and if the unsupervised Uganda program falls under the definition of UBI even when it’s only granted to applicants with a valid proposal. But I give up, you win. And I don’t have to defend Britannica, because it’s so well established.