The Chinese are always, and have been, very concern to what is happening in China.
Even me, a Chinese, who ran away from China when I was very young, and ended up in America and stayed in America for a few decades, still in my spare time, check out what is going on in China.
The "nationalistic" phenomenon for the Chinese people ebbs and flows - it happened back in WW2, when the Japanese invaded China, it happened again during the Korean war, and for a while, in between the Korean war until recently, most Chinese prefer to focus their attention towards themselves.
At first it was for survival, as China under the tutelage of Mao, landed itself in a seemingly endless episodes of man-made disasters. Famines that took away the lives of millions happened. Cannibalism happened, cultural revolution happened, intellectuals were driven to madness and/or suicide happened, and so on...
When Deng took over in the late 1970's, economically speaking China became better. The Chinese people turned towards making money.
That lasted for almost 40 years, and the economy of China has started to flatline, people are getting laid off (and young university graduates couldn't find jobs).
To allay the pent-up anger, the CCP, under the Xi-Li pair, opted for the "nationalistic" approach.
And that coincides with the provocations from Japan. With more and more provocations from Japan, the fuel for the fire of nationalism multiplied.
You gotta understand that the Chinese people, until today, can *NOT* forgive what the Japanese did to them, back in the WW2. That is because, unlike the Germans who issued public apologies to their victims (particularly Jews and Gypsies), the Japanese refused to apologize for the carnage they had done in China.
That bad blood in between the Japanese and Chinese is now exposed in the open.
The CCP of course, ain't stupid. They fully utilize the follies from Japan to add fuel to the nationalism fervor.