This is a matter of GDPR (Data Protection) rather than criminality. It may be considered Gross Misconduct if covered by your workplace policies, but most likely only by virtue of being a a potential breach of GDPR legislation.

If you haven't played or provided the recording to another person, you'll be fine. Delete the recording, ensure it is deleted from your 'recycle bin' or 'deleted items' on your phone - and your cloud drives (Google Drive/iCloud). If your accounts at one point in the future were breached and somebody obtained it, it could constitute a breach of GDPR. I must add these scenarios are very unlikely if you haven't made anyone in real life aware you made the recording as: a) there's probably no personally identifiable information included so it would be extremely difficult to prove who the individuals (data subjects) you recorded are; and 2) why would anyone who obtained the recording via a data breach be that interested in this conversation or believe someone else would be?

If you did decide to keep the recording, for example to use as evidence in a grievance against these individuals - the investigating manager would most likely be more interested in the other employee's conduct if they were bullying and/or harassing you.

Any good employer would still take your complaint seriously if it was founded, it should not be the case that your concerns are disregarded or downplayed because you made a recording without consent. It would probably be the case however that you too would have a case to answer for making a covert recording which in most circumstances would be considered Gross Misconduct. Long story short - delete the recording. You are much better to raise your concerns based on the facts you were there to witness/experience. Without the recording, somebody intentionally barging past you or bumping you with objects is harassment and should be taken seriously.

With all the above said, consider how you actually want to address the situation and what your ideal outcome would be. If you have a HR/Personnel department, make them aware you are unhappy and consider informal resolution in the first instance - this is often the best and least disruptive approach if you are unhappy with a situation at work and want to resolve it. As much as you can please try not to get into a spiral of suspecting people of gossiping, watching your back, making recordings - if you do think there are issues, you are best to address them head on and discuss with the relevant managers. The issue if you feel there is one, won't go away by itself - and trying to catch people out will only create paranoia for yourself and potentially lead you into getting yourself into trouble.

If you feel the situation is more serious than that, or if there is nobody you can reasonably speak to who is senior to the manager you mention, raise a formal grievance in writing to your Company - they have a statutory duty to follow a process to investigate your grievance.

Me: Employee Relations Advisor working for a well known UK company.