In two of the races concerned, in one the race was stopped because the conditions were considered by RD to be too unsafe to continue, an assessment he had also made, just earlier, and in the other his tyre delaminated.
Both Yamaha riders lost the front and dnfed in the recent race which was dry, Rossi saying he had no warning, there have been front end washouts for multiple riders all season, and two of the leading riders had massive high sides in practice, not a feature of recent years.
Something has changed for 3 of the 4 top factory riders this year. Given both the ECU and the tyres were changed this year, either or both may be influential, but I don't see how the influence of one change ie tyres can be confidently excluded.
Whether this was by design, and in particular by a design to help Rossi, is a different question.
I personally think and have consistently argued since 2008 that there should be a wider choice of tyres suited to a variety of bike designs and riding styles. My suspicion rather than a pro-Rossi conspiracy is that Dorna don't actually know what they are doing and may consider a tyre lottery desirable.