Background: So I'm a software developer nearing the end of my probation period at a company I recently started at. After starting I noticed a few things that made the company not a very good fit for me. Mainly working almost exclusively on a legacy product, with very old web technologies, that was promised to me I shouldn't be spending much time on. Only the occasional bug fix but the product was basically EOL. Second, corporate policies like no working from home and/or abroad and having to clock in and out to measure your hours. After about two months I managed to get an interview via a contact at a company this contact was very happy at. They offered me a very competitive offer which would give me more freedom, working with new tech and a significant salary increase.
Question: In the end I decided it would be for me to move since I'm not very happy about the current job. This opportunity came quite late in my trial period so I'm nearing the end and I'm a bit anxious on how to handle the resignation and how they will respond. Besides pulling my manager aside and breaking the news is there anything I can do or say to not burn any bridge (might not be possible) or to just handle things as best as possible?
Also feel pretty bad about having a gap on my resume now. Is this something I should be worried about or are the reasons outlined good if ever asked during a potential future interview?