I've never heard of this and it sounds interesting.
As another example: if I had 2 years pensionable service in job 1, then leave that job and start in job 2 that pays employer contributions from the start. If I transfer pension from job 1 into job 2 pension scheme and I leave job 2 before 2 years, can I keep employer contributions from job 2?
Yes, you can, so long as that transfer from Job 1, is executed, and, the pensionable service is noted, as part of the transfer,
eg the job 2 pension scheme, receive the record of the pensionable service, when the funds transfer is made.
When i dug into this, the idea, is that the 2 year restriction on keeping employer contributions, should (in theory at least) be limited to 2 years Max, for the working lifetime of an individual.
It is there, to prevent employees who change jobs regularly, (which is not uncommon), from being effectively discriminated from keeping employer contributions, as a result of changing employments regularly, which is common in many types of employment.
The key caveat is, for this to work, people in these situations, should waste no time in transferring their funds to their current employer, and that pensionable service, is recorded correctly.
In my experience, some life& pensions organisations can be quite slow to complete this task, and its exacerbated by the fact that there are two parties, a sender and receiver. In one example i experienced, the transferring party did their job quickly, and the receiving company had the funds for more than a month, before crediting my Pension fund account, even though i had made several phone calls and emails, well in advance of the transfer date and again after it had happened.