I found two Covid-19 deaths in mainland China in 2021 which were both reported by the Chinese government and mentioned in Chinese news.
The discrepancy in the two plots likely arises from the sources having different definitions of "China". Taiwan had an outbreak in June 2021, but these data are counted separately on Worldometer whereas they are counted for China by the WHO (hover over Taiwan on this map). (Note that 187 deaths in the WHO screenshot spans a week.)
Hebei province, reported 14 January 2021:
1月13日0—24时,31个省(自治区、直辖市)和新疆生产建设兵团报告新增确诊病例138例,其中境外输入病例14例(上海8例,广东3例,北京1例,河南1例,广西1例),本土病例124例(河北81例,黑龙江43例);新增死亡病例1例,为本土病例(在河北);无新增疑似病例。
Gov.cn, 14 January 2021.
Here's a corresponding video news report:

河北新增1例死亡病例详情公布,系中国内地近8个月以来首次增加, 14 January 2021.
Jilin province, reported 26 January 2021:
1月25日0—24时,31个省(自治区、直辖市)和新疆生产建设兵团报告新增确诊病例82例,其中境外输入病例13例(上海8例,广东2例,福建1例,湖南1例,陕西1例),本土病例69例(黑龙江53例,吉林7例,河北5例,北京2例,上海2例);新增死亡病例1例,为本土病例,在吉林;新增疑似病例3例,均为境外输入病例(均在上海)。
Gov.cn, 26 January 2021.
Here's an example news article about this case.
I didn't find any other cases reported. Searching for site:www.gov.cn "死亡病例1例" after:2021-01-01
only gives these two cases.
Note the linked English CDC China Weekly doesn't list these, but if you click through, they're both listed:
National Health Commission Update on January 14, 2021
..., 1 new death (domestic case, Hebei Province), ...
National Health Commission Update on January 26, 2021
..., 1 new death (domestic case, Jilin Province), ...